Restricted Two Parameter Ridge Estimator

In 2005 Lipovetsky and Conklin proposed an estimator, the two parameter ridge estimator (TRE), as an alternative to the ordinary least squares estimator (OLSE) and the ordinary ridge estimator (RE) in the presence of multicollinearity, and in 2006 Lipovetsky improved the two parameter model. In this paper, we introduce two new estimators, one of which is the modified two parameter ridge estimator (MTRE) defined by following Swindel's paper of 1976. The other one is the restricted two parameter ridge estimator (RTRE) which is derived by setting additional linear restrictions on the parameter vectors. This estimator is a generalization of the restricted least squares estimator (RLSE) and includes the restricted ridge estimator (RRE) proposed by Groß in 2003. A numerical example is provided and a simulation study is conducted for the comparisons of the RTRE with the OLSE, RLSE, RE, RRE and TRE.     

A Bayesian Approach to the Estimation of Expected Cell Counts by Using Log-Linear Models

ABSTRACT

In this article, Bayesian estimation of the expected cell counts for log-linear models is considered. The prior specified for log-linear parameters is used to determine a prior for expected cell counts, by means of the family and parameters of prior distributions. This approach is more cost-effective than working directly with cell counts because converting prior information into a prior distribution on the log-linear parameters is easier than that of on the expected cell counts. While proceeding from the prior on log-linear parameters to the prior of the expected cell counts, we faced with a singularity problem of variance matrix of the prior distribution, and added a new precision parameter to solve the problem. A numerical example is also given to illustrate the usage of the new parameter.     

A Note on Sufficient Conditions for Valid Unmodified t Testing in Correlation Analysis with Autocorrelated and Heteroscedastic Sample Data

Traditionally, sphericity (i.e., independence and homoscedasticity for raw data) is put forward as the condition to be satisfied by the variance–covariance matrix of at least one of the two observation vectors analyzed for correlation, for the unmodified t test of significance to be valid under the Gaussian and constant population mean assumptions. In this article, the author proves that the sphericity condition is too strong and a weaker (i.e., more general) sufficient condition for valid unmodified t testing in correlation analysis is circularity (i.e., independence and homoscedasticity after linear transformation by orthonormal contrasts), to be satisfied by the variance–covariance matrix of one of the two observation vectors. Two other conditions (i.e., compound symmetry for one of the two observation vectors; absence of correlation between the components of one observation vector, combined with a particular pattern of joint heteroscedasticity in the two observation vectors) are also considered and discussed. When both observation vectors possess the same variance–covariance matrix up to a positive multiplicative constant, the circularity condition is shown to be necessary and sufficient. “Observation vectors” may designate partial realizations of temporal or spatial stochastic processes as well as profile vectors of repeated measures. From the proof, it follows that an effective sample size appropriately defined can measure the discrepancy from the more general sufficient condition for valid unmodified t testing in correlation analysis with autocorrelated and heteroscedastic sample data. The proof is complemented by a simulation study. Finally, the differences between the role of the circularity condition in the correlation analysis and its role in the repeated measures ANOVA (i.e., where it was first introduced) are scrutinized, and the link between the circular variance–covariance structure and the centering of observations with respect to the sample mean is emphasized.     

Modified maximum likelihood and modified moment estimators for the three-parameter weibull distribution

This article is concerned with modifications of both maximum likelihood and moment estimators for parameters of the three-parameter Wei bull distribution. Modifications presented here are basically the same as those previously proposed by the authors (1980, 1981, 1982) in connection with the lognormal and the gamma distributions. Computer programs were prepared for the practical application of these estimators and an illustrative example is included. Results of a simulation study provide insight into the sampling behavior of the new estimators and include comparisons with the traditional moment and maximum likelihood estimators. For some combinations of parameter values, some of the modified estimators considered here enjoy advantages over both moment and maximum likelihood estimators with respect to bias, variance, and/or ease of calculation.     

Different estimation methods for the parameters of the extended Burr XII distribution

The extended three-parameter Burr XII (EBXII) distribution has recently attracted considerable attention for modeling data from various scientific fields since it yields a wide range of skewness and kurtosis values. However, it is well known that the parameter estimates have significant effects on the success of a distribution in real-life applications. In this study, modified moment estimators (MMEs) and modified probability-weighted moments estimators (MPWMEs) are used to estimate the parameters of the EBXII distribution. These two considered estimators are also compared with the commonly used maximum-likelihood, percentiles, least-squares and weighted least-squares estimators in terms of bias and efficiency via an extensive numerical simulation. The MMEs and MPWMEs are observed to perform well in varying sample cases, and the simulation results are supported with application through a real-life data set.     

转基因农产品国际法律规制

基于博弈论,分析对比不同博弈模型下,在实然层面,国家作为国际法主体参与转基因农产品 利益博弈已经做出的理性策略选择,以及进而缔结的国际条约;在应然层面,探索国家之间如何进行深 度、多次的合作型博弈,更好地做出策略选择,进而完善转基因农产品国际法律规制,在发展转基因农产 品国际贸易和产业的同时,保障食品安全、动物福利和生态环境。     

战略人力资源管理的实现——一个讨价还价模型

人力资源管理需要面对复杂需求环境与供给难以计量的现实,如何突破人力资源管理因果关系的这种模糊性,实现人力资源管理的战略性成为理论与实践的难题。文章通过静态与动态的讨价还价模型,论证了基于HR胜任力等的HR管理者谈判实力在实现战略人力资源管理过程中的关键作用。     

多孔橡胶粉改性沥青降噪路面材料吸声特性试验研究

为研究多孔橡胶粉改性沥青路面降噪吸声特性,利用驻波管分别对30mm、40mm、50mm厚,孔隙率为20％的多孔橡胶粉改性沥青混合料试件和孔隙率为4％的普通沥青混合料试件进行了不同频率下吸声特性试验．分析了试件厚度、声波频率、材料、孔隙率、表面形态等对试件吸声特性的影响及材料吸声机理,并按1／3倍频测定了不同情况下材料的吸声系数．研究结果表明,随试件厚度的增加吸声系数增大;随入射声波频率增大,材料的吸声系数呈先增大后减小的趋势;多孔隙橡胶粉改性沥青混合料试件比普通沥青混合料试件吸声效果明显提高．因而证明,用多孔隙橡胶粉改性沥青混合料铺筑路面具有较好的降噪效果．     

天线互耦对室内MIMO无线信道容量的影响

考虑多天线间互耦,建立了多天线系统等效网络模型,导出通用耦合系数矩阵。应用互耦补偿方法拓展了室内多输入多输出(MIMO)无线衰落信道模型的研究,数值分析了天线单元间的互耦对室内MIMO无线信道容量的影响。验证互耦对空域相关性无影响的条件,计及互耦要比不计互耦对信道容量的影响要大,但互耦导致的天线方向图畸变可能产生角度分集的效果,从而降低信道的相关性并提高信道容量。     

唐宋徽州交通探析

唐宋时期,随着中原移民的迁入和开发,徽州地区展开了大规模的交通建设。徽人利用山川地理形势,在官府主持或当地士绅和往来商人共同努力下,逐渐凿开了徽州通往外界的水陆交通。水陆交通的建设,使徽人的生活得到改善,同时也加强了政府对徽州的有效统治。与此同时,便利的交通,有利于徽州商品的输出,促进了徽州商业的发展。依靠便利的交通,逐步形成了以徽州为地域商品中心。